Drive for a comber

ABSTRACT

One or both of the lap rollers on which a lap roll is mounted for unwinding purposes is driven with an increasing speed during the winding-off interval so as to maintain the thickness of the lap layer constant. This, in turn, maintains the count of the sliver to be formed in the comber at a constant number. The increase in the lap roller drive can be made dependent upon the length of the lap layer which is unwound from the roll, on the mass of the lap layer delivered to the comber or on the mass of a sliver produced from the combed lap as measured at a point downstream of the comber. The speed may be increased in a stepwise manner or continuously.

The invention relates to a method for feeding a lap which can be woundoff from a lap roll to a combing unit of a comber.

With known combers, as can be seen in CH-PS 625 564 e.g., the lap to becombed out is fed to the comber in the form of a lap roll. During thewinding off of the lap, the lap roll is placed on two lap rollers, ofwhich at least one is driven. The winding off of the lap from the laproll takes place before the front lap roller. The lap wound off in sucha manner reaches via a feed roller into the nip of a nipper jaw and iscombed out at its front end, which extends past the nipper jaw, with thenipper jaw closed by way of a comb cylinder arranged below the nipperjaw. Following the combing out process, the nipper jaw is opened againand the combed out fiber tuft is transferred to a subsequent detachingroller pair. During this detaching process, a top comb inserted into thefiber tuft to be detached can effect an additional combing effect.During the combing process, the nipper jaw effects a to and fromovement. In order to enable a simpler joining of a new lap, the drivenlap roller is disconnected from the drive by a coupling so that both laparbours are freely turnable.

European Patent Application 03 60 064 describes a comber in which afront lap roller is driven by a separate driving motor which istriggered by a control unit. This control unit has the task tochronologically harmonize the controls of the separate driving motor forthe feed rollers, the drive for the lap arbour as well as the drive forthe nipper jaw, the comb cylinder and the detaching roller.

The lap roll rests freely on the two lap rollers with its entire weight(20-25 kg). As a result, an indentation is created in the roll inrelation to its circumferential diameter based on the elasticity of thelap. After passing the resting place, the lap expands to its originaldiameter minus the thickness of a lap layer. With a decreasing lapdiameter and hence decreasing weight, this indentation depth decreases.In order to ensure a better carrying, the lap rollers are toothed.

The circumferential speed of the lap is greater on its circumferentialdiameter than the circumferential speed in the area of the leastdistance between the center axis of the lap and the resting surface i.e.a contact surface roller. This results in that the more the diameter andhence the weight of the lap decreases, the smaller the indentationdepth, and hence also the penetration of the lap into the toothing, andthe difference between the circumferential speed in the area of itsexternal diameter and the circumferential speed in the area of the leastdistance between center axis of the lap and the contact surface of thelap roller. Based on these different speed relationships, a differentfeeding speed of the lap can result depending on the diameter or weightof the lap roll. In addition to the described influence of the changedindentation depth on the supplying speeds of the lap, with decreasinglap weight the changed dynamic interaction between the intermittingdrive of the feed roller and the constant drive of the lap roller alsoinfluences the changing of the supplying speed during the winding-offprocess of a lap roller. By way of the mentioned influences, the tensiondraft of the lap changes between the lap roller and the feed rollerduring the winding-off process.

From this results, as investigations have shown, that at the beginningof the winding off process, the combing aggregate is fed a thicker lapfor combing out than toward the finish of the lap roll.

This deviation is generally termed as drift and may be of up to 5%,depending on the structure of the lap roll, material and otherparameters.

A separate drive for the lap rollers, which is controlled by a controldevice, is also shown in Swiss Application No. 140/90, filed Jan. 17,1990. The control of the separate drive for the lap rollers is herenecessary for the joining process of a new lap in the nipper jaw of thecomber. A continuous adjustment of the lap roller drive during thewinding off process is not provided here.

These differences emerging during the winding off process of a lap of amass fed for combing has a negative effect on maintaining the count of asliver created following the combing aggregates.

The combers are, as a rule, equipped with eight combing heads, eachbeing fed a lap roll for combing out. The lap combed out in this way isthen collected to a sliver. This way eight slivers are created which areguided, after corresponding deflection, juxtapositioned to a subsequentdrafting arrangement. The slivers drafted in this drafting arrangementare collected into a single sliver which is subsequently placed, as arule, in a can.

Between the drafting arrangement and the can coiler there is, as e.g. tobe taken from the E7/5 of Rieter company, a sliver monitoring devicewhich monitors the count of the exiting sliver.

The drift of up to 5% created during the winding off process of the lap,as previously described, can be measured with this sliver monitoring ina time-delayed manner.

It is therefore the object of the invention to propose a method or adevice for the drive of the comber, or of the lap rollers, which enablesthe formation of an even sliver at the comber and ensures a continuousfeed of a lap mass to a combing unit, independent of the size of the laproll.

Briefly, the invention provides a method of feeding a flap from a laproll comprising the steps of mounting a roll of lap on a pair of laprollers, driving at least one of the lap rollers in a direction tounwind a layer of lap from the lap roller during a winding-off integraland increasing the speed of the lap roller during the winding offinterval in order to maintain the constant thickness in the lap layerunwound from the lap roll.

The technique employed may change the speed of each of the driven laprollers or only one lap roller during a winding-off integral.

Here, the expression "winding off interval" refers to the period betweenthe placing of a new and full lap and the winding off of the lap from atube of the lap roll. The invention is not restricted to both laprollers being connected to the drive, but applies also to the drive ofonly one lap rollers with the other lap rollers being carried along byfriction via the lap roll.

It is proposed that the speed of the driven lap rollers is increasedwithin the winding-off interval.

In a further embodiment of the invention it is proposed that the laprollers are driven by an independent drive which can be controlled oradjusted independently from the drive of the combing aggregates.

The term combing aggregates generally is understood to comprise a nipperjaw, feed roller, top comb, comb cylinder and the detaching roller.

By way of the proposed independent control and adjustment, an adaptionof the speed increase of the lap rollers during a winding off intervalis ensured for different lap feeds. Also, in this way corrections of thespeed changes can easily be conducted.

As a rule, the total length of the wound up lap is known from theprocess of the lap formation which is upstream of the comber. Based onthe required supplying speed of the lap to the combing aggregates, aconclusion results concerning the time interval in which the lap iswound off the tube again.

It is therefore proposed to adjust the speed adaption of the lap rollersvia the control of the drive according to the measure of the wound offlap length. Here, for the purpose of adapting, various parameters can beused. These parameters can e.g. be experimental or testing values whichpreset a corresponding adaption of a speed increase. The speed can beincreased continuously based on a curve or discontinuously within acertain time interval. A further determination for finding theparameters which serve for adjusting the drive of the lap rollers is adirect detection of the mass of the wound off lap between the front laproller and a feed roller of a nipper jaw via a capacitive measuringorgan. The measuring values hereby determined result in a signal incomparison with the preset value which brings about a readjustment ofthe drive of the lap roller.

As further proposed, there also exists the possibility to detect themass of the sliver formed following the combing aggregates via ameasuring device. Here the drive of the lap rollers is readjusted incase of a drifting off from a preset value. Here, however, thecomber-waste loss must be taken into consideration. A control of thedrive of the lap roller by monitoring the lap weight is alsoconceivable.

It is further proposed to automatically return the drive of the laprollers back to their beginning speed at a lap roll change. This way, itis ensured that for the processing of each lap roll, the same conditionsare created. Via a sensor, as e.g. described in CH-PS 572 529, thewinding off of the end of the lap from the tube is monitored. Thissignal can be used for returning the drive of the lap arbours to itsbeginning position.

When using an automatic lap joiner for a new lap roll it is necessary tocreate an overriding possibility of the speed and of the direction ofrotation of the lap rollers in relation to the beginning speed.

The proposed method for adapting the speed during the winding offinterval is to be applied advantageously when a block change of the lapat the comber is effected. This means that all laps are changed at alleight combing heads simultaneously. This ensures that the diameterdecrease during the wind-off of the lap is equal at all combing heads.

It is however also possible to effect the method according to theinvention at a comber with a so-called "wild change". The expression"wild change" here refers to the lap rolls being changed singlyaccording to their finishing. For the realization of the methodaccording to the invention, it would be necessary in this case toallocate to each single combing head a separate drive for the laprollers in order to meet the different finishing of the lap roll of eachcombing heads.

These and other objects and advantages of the invention will become moreapparent from the following detailed description taken in conjunctionwith the accompany drawings wherein:

FIG. 1 shows a schematic sideview of a combing head with a controldevice for the lap rollers.

FIG. 2 shows an enlarged partial view according to FIG. 1.

FIG. 3 shows a reduced view according to FIG. 1 with a schematicallyrepresented drafting arrangement and a layer coiling.

FIG. 4 shows a diagram for a possible speed adaption per wind-offinterval of a lap roll.

FIG. 5 shows a schematic partial view of a combing head according toFIG. 1 with a possible measuring organ for the lap.

FIG. 1 shows a combing head 1 in schematic sideview of a comber.Usually, eight such combing heads 1 are installed on a comber. Theexemplary embodiment is shown and described on only one combing head forclarity, the listed driving units being used by all combing headstogether, however. This is required in particular for combing machinesin which a previously described block change takes place. The drivingshafts hence extend over the entire width of the combing heads, with thedrive taking place centrally from one side of the combing heads. It ishowever also conceivable to allocate separate driving units or controlsto each combing head or to groups of combing heads.

In its upper area the shown combing head 1 is provided with a receptacle2 for a lap roll 3. The lap roll 3, which below will also be referred tosimply as "lap", rests freely on two lap rollers 4 and 5 which arepivoted in a frame 6. Here the front lap roller 4 is connected to amotor 8 via a drive line 7. The motor 8 can also be arranged directlyflush with the lap roller 4. Further, it is also conceivable to arrangebetween motor 8 and lap roller 7 a transmission gearing. This is,however, only of secondary importance and is merely mentioned here. Themotor 8, e.g. an electric motor, is controlled via a control unit 9. Thelap layer 10 wound off from the lap 3 which rotates in a clockwisedirection Z is guided over a guide roller 11, on which a spring weightedfeeler roller 12 is placed. An incremental transducer (impulsetransmitter) 13 is laterally attached to determine the speed of the roll12. The signal of this impulse transmitter 13 is transmitted via a path14 to a controller 15 from which, after conversion of these signals,corresponding control pulses are transmitted to the control unit 9. Thelap layer 10 passes down to a combing aggregate 16. This combingaggregate 16 is formed by a nipper jaw 17, in which a feed roller 18 ispivoted. This feed roller 18 is as a rule rotated by a relative movementbetween the upper and lower nipper jaw via a ratchet drive (not shown).The nipper jaw 17 is pivoted via an articulated arm 21 on a combcylinder axle 22 of a comb cylinder 23 provided with a combing segment24. Seen in conveying direction F of the lap layer 10 following thenipper jaw aggregate 17, there are the detaching rollers 25. The driveof the detaching rollers 25 of the comb cylinder 23 and of the drivingshaft 20 for the nipper jaw 17 takes place by a central driving unit 26which is controlled via a control unit 27.

In order to scan the lap 3, or to monitor the finishing of the lap layer10 from the tube 28, a sensor 29 directed at the tube is attached. Thesignals produced by sensor 29 upon finishing of the lap are transmittedto the control units 9 and 27 via a path 30.

In FIG. 2, the lap 3 as well as the lap rollers 4 and 5 receiving thelap 3 are shown in enlarged representation. In the area of the rest 30of the lap roller 4 and of the rest 31 of the lap roller 5, the lap isindented in relation to its exterior diameter D. This indentation withthe indentation depth is created by the elastic and giving lapstructure. The resting area of the exterior circumference 32 of the laparbour 4 has a minimum distance R1 to the center of the lap 3. Inrelation to the diameter, 2×R1=D. After passing the rest 30 the lap rollexpands to approximately its original diameter minus the wound off laplayer of the thickness S. As has been hinted at schematically, thedriven lap roller 4 is provided with a toothing 47. The rear arbour 5could also have such a toothing 47. At the lap roller 5, the possibilityof a bearing of the roller in a bearing bracket 49, which rests on abalance 50 and hence enables the monitoring of the resting lap weight,is indicated by dash-dots.

With friction via the exterior circumference 32 of the driven lap roller4, the lap 3 is turned in the winding-off direction Z and the lap layeris wound off behind the rest 30 from the lap 3. Departing from that thetransmission of the rotating movement of the lap roller 4 in the area ofthe rest 30 takes place with the diameter D1, with a diameter D1 inrelation to the diameter D a lower circumferential speed is achieved andhence a different feeding speed for the lap 10. On the other hand, thecircumferential speed of the lap roller 4 is constant, varying howeverin the toothing. This means, that with a decreasing lap roll diameter Dand hence a decreasing weight of the lap 3, this indentation depth Xdecreases and the lap roll diameter D approaches the diameter D1 and thelap is pressed less strongly into the toothing 47 of the lap rollers.Hence, the speed differences in relation to the diameter D or D1decrease. This means that the feeding speed of the lap layer 10approaches with decreasing lap diameter D the speed at diameter D1produced via friction.

Decisive for the feeding speed of the lap layer 10 is the winding offdiameter D and the penetration depth X of the lap into the toothed laparbour 4. From this results that the greater the difference betweens Dand D1, or the indentation depth X, the greater the difference betweenthe actual feeding speed of the lap layer 10 and the rotating speedproduced in the area of the diameter D1. The conclusion from thisconsideration is that the feeding speed of the lap layer 10 at thebeginning of the winding off process, i.e. with full lap roll, isgreater than at the end of the winding off process.

Investigations have shown, however, that not only is the influence ofthe indentation depth of the lap with decreasing lap weight decisive forthe changed feeding speed, but that also the changed dynamicinterrelation between the feed roller drive and lap arbour drive play arole. Which one of these two criteria now is decisive for the formingdrift depends on the given material and drive conditions.

Experiments have shown that these differences result in a drift of up to5%.

For the combing process itself no disadvantages result, for between thelap roller 4 and the feed roller 18 a so-called tension draft is presentwhich is greater than 1.0.

By way of the previously described drift keeping the count of the sliverformed following the combing aggregate at the comber cannot beguaranteed. This however is absolutely required in order to achieve aneven thread at the following spinning processes. This however is to beguaranteed with the method proposed according to the invention, i.e. thecreated drift is compensated by the proposed method. The exemplaryembodiment according to FIG. 1 shows a possible embodiment for realizingthe method and is now more particularly described:

The lap roller 4 driven via the motor 8 puts the lap 3 into rotatingmovement via friction. The lap layer 10 wound off thereby is guideddownward via the guide roller 11 and reaches into the action area of thefeed roller 18. This feed roller 18 is driven intermittently by themovement of the upper nipper jaw via a ratchet drive (not shown) andconveys the lap layer 10 into the area of the nip of the nipper jaw 17.If the nipper jaw 17 is located in a rear position (not shown), then itis closed and a part of the lap layer 10, a so called fiber tuft,extends out of the closed nipper jaw 17 and is combed out by the combingsegment 24 of the rotating comb cylinder 23. Subsequently, the nipperjaw 17 moves towards the front again and opens. Here the combed outfiber tuft is given off to the detaching roller pair 25 between which atuft, which has already been combed out, is clamped. For reasons ofsimplicity the representation of an additional fixed comb which reachesfrom the top into the fiber tuft to be given off, as usedconventionally, has been left out.

The drive of the detaching roller 25, of the comb cylinder 23 and of thedriving roller for the nipper jaw 17 takes place from the centraldriving unit 26 which is controlled via the control 27. The control 27and the control unit 9 are interconnected via a path 33 and can beharmonized to each other. This harmonization refers to the normalcooperation during the nipping of the comb, here a readjustment of themotor speed 8 due to a drift correction takes place independent of thiscooperation. For determining the wound off length of the lap layer 10the roller 12 which is spring weighted via a spring 34 is arranged onthe guide roller 11, the lap layer 10 moving through these two. Duringsupply of the lap layer 10, the feeler roller 12 is put into rotation,this rotational movement being detected via the impulse transmitter 13or an incremental transducer. This rotational movement is converted intoa corresponding signal via controller 15 and supplied to the controlunit 9.

In the present example, a readjustment of the motor speed 8 and hence ofthe speed of the lap roller 4 takes place in temporary intervals inrelation to the winding off length of the lap layer 10 determined by thefeeler roller 12. The magnitude of the readjustment takes place in theshown example, as is visible in the diagram shown within the controlunit, gradually, based on progressive ratios stored in the control unit9. These preset adjustments of the speed based on wound off length unitsL of the lap layer 10 results from effected experiments and experimentalvalues which have been determined.

It is, however, also possible to do without the feeler roller 12 and toadjust the speed of the motor 8 based on experimental values in a linearand continuous manner from the beginning of the winding off process(FIG. 4). This FIG. 4 also shows that the speed N1 of the motor 8increases in a linear manner up to the change of the lap t1 to a valueN2 and subsequently is guided back to the basic speed N1. The samelinear increase takes place at the next winding off process up to thenext lap change at T2.

It is also conceivable, as indicated in FIG. 2, to caliper the weight ofthe lap roll 3 via a balance 50 which carries the rear lap arbour 5 viaa bearing bracket 49. According to the decreasing weight of the lap, thedrive of the lap roller 4 can be controlled.

FIG. 5 shows a further possibility which serves for controlling the laproller drive. Here, following the lap arbour 4, the mass of the woundoff lap layer 10 is measured via a capacitive measuring organ andcompared with an actual value preset in a controller 37. With a driftforming in the course of the winding off process, the controller 37emits a signal in case of a deviation from the set value via the path 36to the control unit 9 which readjusts the motor 8. This way a closedcontrol circuit is created and the motor 8, or the speed of the laproller 4, is continuously readjusted when deviating from a set value.

FIG. 3 shows a similar control unit according to FIG. 5. Here, however,there is a detection of an unevenness of a sliver 38 which has beenformed by a drafting arrangement 39 which is downstream of the combingheads 16. For reasons of simplicity, the arrangement of the draftingarrangement and of the following devices have been turned by 90° aroundthe axis X. The sliver 38 is monitored via the measuring organ 40 forits count, or the mass per unit of length. The signal created here issupplied to a controller 41 in which a comparison of the actual valueand the set value is effected. If the actual value deviates from the setvalue, a control signal is transmitted to the control unit 9 via a path42 for readjusting the motor 8. This is also a closed control circuit,however, readjustment taking place time-delayed. In this kind ofadjustment, however, the influence of the comber-waste loss must betaken into account in order to avoid erroneous measurements.

The sliver 38 guided through the measuring organ 40 reaches a cone wheel45, via a guide roller 43 and calender rolls, which can be driven inrotation, and which eventually places the sliver 38 in a can 46 forfurther conveyance to the following procedure steps.

In the exemplary embodiments of FIG. 1, 3, and 5 the lap is allocated asensor 29 to monitor the finishing moment of the lap 3. This means, assoon as the white lap layer 10 has been wound off the black tube 28, thesensor 29 recognizes the black surface of the tube and transmits asignal to the control 9 for the motor 8 and to the control 27 for thecontrol unit 26. This way, on the one hand the drive unit 26 is shutdown via the control unit 27 as well as the drive 8 interrupted by thecontrol unit 9. Simultaneously, with this interruption, the speed markfor the triggering of the motor 8 is reset to the basic speed N1 whichcomes into effect again with the beginning of the winding off process ofa new lap. As previously already described, the basic speed N1 can beoverriden until the beginning of the normal winding off process by usingan automatic winding changer.

We claim:
 1. A method of feeding a layer of lap from a lap rollcomprising the steps ofmounting a roll of lap on a pair of lap rollers;driving at least one of said lap rollers in a direction to unwind alayer of lap from said lap roll during a winding-off interval; andincreasing the speed of said one lap roller during said winding-offinterval to maintain a constant thickness in the lap layer unwound fromthe lap roll.
 2. A method as set forth in claim 1 which furthercomprises the steps ofmeasuring the length of the lap layer unwound fromthe lap roll during said winding-off interval; and increasing the speedof said one lap roller in dependence on the measured length of theunwound lap layer increasing during said winding-off interval.
 3. Amethod as set forth in claim 1 wherein said step of increasing the speedof said one lap roller is effected in one of a continuous manner and astep-wise manner.
 4. A method as set forth in claim 1 which furthercomprises the steps ofmeasuring the weight of the lap roll remaining onsaid lap rollers during said winding-off interval; and increasing thespeed of said one lap roller in dependence on a decreasing measuredweight of the lap roll.
 5. A method as set forth in claim 1 whichfurther comprises the steps ofdirecting the layer of lap unwound fromthe lap roll to a combing unit of a comber for combing therein;thereafter forming a sliver from the lap layer combed in the combingunit; measuring the mass of the sliver downstream of the combing unit;and increasing the speed of said one lap roller in dependence on achange in the measured mass of the sliver during said winding-offinterval.
 6. A method as set forth in claim 1 which further comprisesthe steps ofdirecting the layer of lap unwound from the lap roll to acombing unit of a comber; measuring the mass of the lap layer directedto the combing unit; and increasing the speed of said one lap roller independence on a change in the measured mass of the lap layer during saidwinding-off interval.
 7. A method as set forth in claim 1 which furthercomprises the steps ofmounting a fresh lap roll on said rollers afterunwinding of a previous lap roll therefrom; and automatically resettingthe speed of said one lap roller from an increased speed level to alower preset speed for initial unwinding of a lap layer from said freshlap roll.
 8. A method as set forth in claim 1 which further comprisesthe steps ofdirecting the layer of lap unwound from the lap roll to acombing unit of a comber; driving the comber independently of the speedof said one lap roller; and increasing the speed of said one lap rollerindependently of the operation of the comber.
 9. A method of feeding alayer of lap from a lap roll comprising the steps ofmounting a roll oflap on a pair of lap rollers with one of said rollers forming anindentation in said roll of lap; driving at least said one lap roller ina direction to unwind a layer of lap from said lap roll during awinding-off interval; and increasing the speed of said one lap rollerduring said winding-off interval to compensate for a change in lapunwinding speed due to said indentation and to maintain a constantthickness in the lap layer unwound from the lap roll.
 10. A method asset forth in claim 9 which further comprises the steps ofdirecting thelayer of lap unwound from the lap roll to a combing unit of a comber;driving the comber independently of the speed of said one lap roller;and increasing the speed of said one lap roller independently of theoperation of the comber during said winding-off interval.